the american environment, miserable during the 1970s. we had acid rain smog. our rivers and lakes terribly polluted. 40 years later, population has increased by 50%. the environment is much smarter and more sustainable. >> jonathan, your last chapter is "how to make babies." do you doubt that people don't sflm. >> you know, a lot of people -- it's a complicated subject. >> i know. it is a complicated subject. it's more than just having sex. you have a bigger plan in mind. thank you, jonathan last. >> thank you. >>> and gabby giffords made a plea to congress last week to do something about gun violence. this morning, the young man who helped save giffords, remember him, writes a note to self. daniel hernandez jr., next on "cbs this morning." >>> president obama is among those who consider daniel hernandez jr. a hero. hernandez is the 20-year-old intern who helped save congresswoman gabby giffords during the deadly mass shooting in arizona two years ago. this morning, he writes a letter of advice for our ongoing series, "note to self." >> dear daniel, at the age